First, writing is hard. And slow. I've been writing my current novel two years now. I'm nearing the end (I hope) but I know I have a least one more round of editing and beta readers, before I begin the process of publication.

Here are some more things I've learned about the writing process:

So much of a book changes. I took my time in my first draft, thinking that would lessen the editing later, but so much still changed in drafts 2 and 3. Pacing, plot tangents, the story world, characterization. There's more I'll change in draft 4.

It's hard to portray the balance of your character's traits. (It gets easier after draft 1, when you get to know them better.) Most of my characters in Beyond the Mountain (YA fantasy) are uneducated, and I struggled to make their dialogue sound right. I wanted informal without making them sound stupid, and also without sounding too modern. And I wanted my main character scared but not a fraidy cat, grieving but not a cry baby, pushing forward but not just brushing her grief away like she's over it now.

It's both fun and frustrating to filter your language through the confines of the story world. In an equatorial setting (like in Beyond the Mountain), "ice cold" and "everybody froze" don't work. No one in the empire have never experienced ice. Likewise, they can't throw a wrench in the works or touch base or put someone six feet under. This forces me to create more original turns of phrase--it's fun, but sometimes a challenge.

Research can be hard, at least for my pre-industrial, equatorial world. For example, information about plants often revolves around the seasons (which are very different in the tropics--no summer, spring, etc.), and I find little on how certain herbs are made into traditional medicines, how well/fast they work, etc.

Some things I've learned about myself specifically:

I like grey. Charcoal, ash, smoke. Partly I like grey, partly I like those things, partly I like those words. They end up in my writing a lot.

I over-research. And get distracted by interesting information. I look up uses for banana plant fibers, and before I know it I've spent an hour reading how banana beer is made.

I'm a perfectionist. Even when I know there will be later drafts and edits, I struggle to get words written. I spend too long agonizing over the perfect word choice.

It's tough to choose between insignificant options. Should this tiny house have two rooms, or just one? Should the city have walls and gates? Would the poorer sections of town have pointed roofs, or flat roofs where residents can cook/hang laundry/grow plants? Overall (unless I happen to write a sequel where having a city gate or not could be important) these things don't really matter, but I agonize.

I like things to be accurate. Or at least plausible. It always bothers me in movies and books when characters do impossible things. Not so much when Legolas runs up falling rocks midair--because that's obviously a silly liberty for entertainment's sake. But more subtle things, like a castle lit with torches that: A) last more than a couple hours, B) light the whole room/hall, and C) don't produce any smoke. My work in progress is fantasy, so I have a bit of liberty in historical accuracy vs. anachronism, but I still want everything to be realistic and plausible.

I love worldbuilding. Most fantasy I've read is kinda-sorta based on medieval Europe. But the more I research other places, times, and cultures, the more excited I get about possible worlds for future books. Sometimes I get most excited over mundane details of the everyday lives of everyday people.

What I've learned about the world:

As a writer, I know every character is the hero in his/her own story. Even the bad guy. I as the author have to know why he is the way he is. Turns out, he's also the hero of his own story.

That means in real life, every person is the hero of his/her own story. People (usually) aren't just out to be jerks. They've been through stuff you don't know about, and were raised a certain way, and have experienced different relationships and successes and disappointments than you have. That doesn't excuse them (or you) for acting like jerks, but you don't know everything about them. They have their own side of the story.

The world is full of story ideas. Since everyone is the hero of his own story, and everyone has problems they deal with, even everyday people with first world problems can spark a story readers identify with. Paying attention to relationship complexities and personality quirks and worldviews can help you in your writing. But even if you're not a writer, when you get to know different sorts of people (different in culture, wealth, sex, religion, tastes, physical limitations, emotional health, whatever) you start to realize that people are at the same time A) more alike than you thought, and B) more varied than you thought.